Yay, nostalgia!

I remember the Backlot game and the Nightfall Incident game the most.

Backlot was goooood

Mata-Nui Online Game was great, I have good memories of playing that.

I loved lots of them. I liked backlot, that dino game, and also the lego knights games. At one point bionicle even had its own website with different games.
(I also liked creature from the crusty krab.)